SEP IRA vs Solo 401k: Which Is Right for You

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By The Money Floor Editorial Team · Source-verified · Last updated July 2026

If you’re self-employed or running a side hustle with real income, the SEP IRA vs Solo 401k decision is one of the most important retirement choices you’ll make without an employer plan — because you don’t have an employer doing this for you. Both accounts let you shelter a lot more money from taxes than a standard IRA. Both are designed for people without a traditional workplace plan. But they work differently, and the wrong choice could mean leaving thousands of dollars in tax savings on the table every year. This post breaks both options down in plain English so you can pick the right one for your situation and move on.

Before we go further: if you’re not sure whether to prioritize retirement savings or other financial goals right now, check out our guide on how to save for retirement when you have no 401k at work — it covers the bigger picture before you zoom in on a specific account type.

Option A: The SEP IRA

A SEP IRA (Simplified Employee Pension) is exactly what the name promises: simple. You open one at a brokerage like Fidelity or Vanguard, you contribute money, and you get a tax deduction. That’s mostly it. No annual IRS filings. No complex rules about employee vs employer contributions. Just a clean, functional retirement account built for self-employed people and small business owners.

How Much Can You Contribute to a SEP IRA in 2026?

According to the IRS, the 2026 SEP IRA contribution limit is the lesser of 25% of net self-employment compensation or $70,000. The “net” part matters. Self-employed workers calculate net earnings after subtracting half of their self-employment tax and the SEP contribution itself. The effective real-world rate works out closer to 20% of your gross self-employment income.

Here’s what that looks like in practice. Say you earn $80,000 in net self-employment income. Twenty percent of $80,000 is $16,000. That’s your approximate SEP IRA contribution for the year. You deduct that from your taxable income, which is a real, meaningful tax break.

SEP IRA Pros

• Dead simple to open and maintain — no annual IRS reporting (no Form 5500)
• High contribution limits compared to a regular IRA
• You can open one and contribute up until your tax filing deadline, including extensions (so by October 15 for the previous tax year)
• Works even if you have employees — though you’d have to contribute the same percentage for them too

SEP IRA Cons

• No Roth option — contributions are always pre-tax (traditional only)
• No catch-up contributions for people 50 and over
• Lower effective contribution ceiling at lower incomes compared to a Solo 401k
• No loan provision — you can’t borrow against it

Who the SEP IRA Is Best For

The SEP IRA fits people who want simplicity above all else. Freelancers, consultants, and side hustlers who earn good money but don’t want to deal with paperwork will find it easy to use — though it’s worth knowing how gig work and quarterly taxes factor into your overall self-employment tax picture. It also works well if you have employees, since the Solo 401k shuts that door entirely.

Option B: The Solo 401k

A Solo 401k (sometimes called an Individual 401k or Self-Employed 401k) is a traditional 401k adapted for self-employed people with no employees. It works exactly like the 401k you had at a corporate job — except you wear two hats. You contribute as the employee, and then you also contribute as the employer. That two-layer structure is what makes it so powerful.

How Much Can You Contribute to a Solo 401k in 2026?

The 2026 Solo 401k contribution limit follows the same $70,000 ceiling as the SEP IRA. But the path to get there is very different. As the employee, you can contribute up to $23,500 of your net self-employment income (or 100% of it if you earn less than $23,500). Then, as the employer, you can add up to 25% of your net self-employment compensation on top of that.

That structure matters enormously at lower income levels. Someone earning $50,000 in self-employment income could contribute roughly $23,500 as the employee, plus around $9,293 as the employer contribution, for a total of about $32,793. A SEP IRA at the same income level would cap out around $10,000. The Solo 401k wins by a wide margin when your income is lower or moderate.

If you’re 50 or older, the IRS also allows a $7,500 catch-up contribution on top of the $23,500 employee limit in 2026. That brings your employee-side maximum to $31,000 — before any employer contribution. For late starters, this is a huge deal. Our catch-up savings guide for people at 35, 40, and 45 has more on making the most of these provisions.

Solo 401k Pros

• Higher effective contributions at lower and moderate incomes
• Roth option available (contributions grow tax-free, withdrawals in retirement are tax-free)
• Catch-up contributions for ages 50 and over
• Loan provision — you can borrow up to 50% of your balance or $50,000, whichever is less
• More flexibility for tax planning: you can split contributions between traditional and Roth

Solo 401k Cons

• More complex to set up and administer
• Once your account balance exceeds $250,000, you must file Form 5500-EZ annually with the IRS
• You must open the account by December 31 of the tax year you want to use it (not extended to tax filing deadline)
• Zero employees allowed — the moment you hire someone other than a spouse, the account becomes unavailable

Who the Solo 401k Is Best For

The Solo 401k is the right tool for self-employed people who want maximum contribution power and tax flexibility. Sole proprietors, single-member LLC owners, and independent contractors with no employees will get the most out of it. If you’re also interested in how HSA investing stacks up as a parallel tax-advantaged vehicle, our post on investing your HSA for the triple tax advantage is worth reading alongside this one.

SEP IRA vs Solo 401k: Side-by-Side

Which One Should You Choose?

Here’s the honest answer, broken down by situation.

Choose a Solo 401k if:

• You have no employees (other than a spouse)
• Your net self-employment income is under $150,000 and you want to maximize what you put away
• You’re 50 or older and want those catch-up contributions — an extra $7,500 per year is real money
• You want the Roth option for tax-free growth in retirement
• You want the flexibility to go traditional some years and Roth others, depending on your income

At a net income of $60,000, the Solo 401k lets you contribute roughly $35,793 in 2026 (employee plus employer). The SEP IRA at the same income gets you to roughly $12,000. That gap is enormous, especially if you’re starting late. Our retirement savings guide for late starters explains exactly why contribution levels matter so much when time is shorter.

Choose a SEP IRA if:

• You have employees (other than a spouse) who would trigger Solo 401k disqualification
• You want to open your retirement account quickly with zero friction
• You’re a high earner (above $200,000 in net self-employment income) and the employer-only contribution structure of the SEP IRA gets you close to the same $70,000 cap anyway
• You found out about this in March and need to open something before your April tax deadline — the SEP IRA’s extended setup window buys you more time

What if you can only contribute a little right now?

Both accounts accept small contributions. There’s no minimum. If you can only put in $100 a month ($1,200 a year), either account works fine. At that level, the Solo 401k’s higher ceiling doesn’t matter yet. What matters is starting. You can always switch or open the second account type later once your income grows.

The IRS publication on SEP plans and their Solo 401k guidance both confirm there’s no minimum contribution required in any given year — you’re never locked into a specific amount. That flexibility is helpful when income is variable, which it usually is when you’re self-employed.

For a broader look at all the tax-advantaged accounts available to self-employed people, Investopedia’s self-employed retirement plan guide is a solid reference with current 2026 figures.

What about both?

You can’t contribute to both a SEP IRA and a Solo 401k for the same business in the same year — the combined limits still cap at $70,000. But if you have a full-time job with a 401k and self-employment income on the side, you can maintain both a workplace 401k and a Solo 401k. The total employee contribution across both still can’t exceed $23,500 in 2026. That’s a detail worth knowing before you assume you have two full limits to work with.

What to Do This Week

Don’t let this decision sit. Here are the steps to take right now.

1. Figure out your approximate net self-employment income for 2026 so far. Multiply by 20% to get a rough SEP IRA contribution estimate. Then check whether a Solo 401k’s $23,500 employee contribution would let you contribute more.
2. If Solo 401k wins, open one at Fidelity or Vanguard before December 31. The account must exist by year-end even if you contribute later.
3. If SEP IRA wins, or if it’s already past December 31, open a SEP IRA by your tax filing deadline — you have until October 15 if you file an extension.
4. If you’re not sure, open the Solo 401k. You can always contribute a small amount and upgrade from there. You can’t undo missing the December 31 setup deadline.

Frequently Asked Questions

What is the difference between a SEP IRA and a Solo 401k?

A SEP IRA is an employer-only contribution account that’s simple to set up and maintain, with a 2026 limit of up to $70,000 based on 25% of net self-employment compensation. A Solo 401k uses a two-layer contribution structure (employee plus employer), which allows higher contributions at lower income levels and also offers a Roth option and catch-up contributions for people 50 and over.

Which has higher contribution limits in 2026 — SEP IRA or Solo 401k?

Both share the same absolute ceiling of $70,000 in 2026, per the IRS. But the Solo 401k reaches that ceiling at lower income levels because the $23,500 employee contribution is a flat amount, not a percentage of income. For most self-employed people earning under $200,000, the Solo 401k allows larger annual contributions than a SEP IRA at the same income.

Can I have both a SEP IRA and a Solo 401k?

Not for the same self-employment business in the same year. The $70,000 total limit applies across both. However, if you have a day job with a 401k and a separate self-employment business, you can maintain a Solo 401k for the self-employment income. Just know the employee contribution limit of $23,500 in 2026 applies across all plans combined.

Can I open a Solo 401k if I have employees?

No. A Solo 401k is only available to self-employed individuals with no employees other than a spouse. The moment you hire a non-spouse employee, you must shut down the Solo 401k and transition to a different plan type. The SEP IRA does allow employees, though you’d be required to contribute the same percentage for them as you contribute for yourself.

What is the deadline to open a Solo 401k for 2026?

You must open the Solo 401k account by December 31, 2026, to use it for the 2026 tax year. You can make the actual contributions up until your tax filing deadline (including extensions). This is different from the SEP IRA, which can be opened and funded any time up to your tax filing deadline, including extensions through October 15.

Is there a Roth option for a SEP IRA or Solo 401k?

The Solo 401k offers a Roth option, allowing after-tax contributions that grow tax-free and can be withdrawn tax-free in retirement. The SEP IRA does not have a Roth version — all SEP IRA contributions are pre-tax (traditional). If tax-free retirement income is a priority for you, the Solo 401k is the only self-employed account that gives you that option directly.